Preventing erosion of core boxes opposite the blow holes thereof



y 1957 R. L. OLSON 2,800,690

PREVENTING mosrou 0F coma Boga OPPOSITE THE BLOW HOLES THER Filed Dec. 20, 1955 ZZ WEHZUF flew/M0 L ULsom fi @uwt- PREVENTING ERQSION F CORE BOXES OPPUSITE THE BLQW HOLES THEREOF Richard L. oison; Chicago, llll.

Application December 26, 1955, Serial No. 554,219 6 Claims. c1. 22*13 The present invention relates toimprovements in the art of blowing sand cores, and more particularly concerns substantial control of the problem heretofore met in erosion of the core box surfaces opposite the blow holes or tubes resulting from forceful impingement of airborne sand thereagainst incident to charging the core boxes with sand from a core blowing machine.

Heretofore the erosion that is controlled by the present invention necessitated constant repair of the core boxes and loss of core production while the repairs were being made. Since the erosion cavitates the core box surface at and about the point of impingement of the sand thereagainst the core contours are affected undesirably, and it has been necessary to repair the pits and cavities by filling the same.

According to the present invention, however, I have provided a method and means for providing a protective barrier on the surface of sandtcore boxes opposite the blow holes or blow tubes whichwill effectively prevent the detrimental action of the impinging sand. It is therefore an' important object of the invention to protect internal or cavity surfaces of core boxes against sand erosion.

Another object of the invention is to provide an improved method of protecting core box surfaces against the erosive effect of sand blown into the core box cavities.

A further object of the invention is to provide improved means for protecting internal or cavity surfaces of core boxes from the erosive efiect of sand blown into the core boxes.

Still another object of the invention is to provide an improved method of and means for protecting surfaces within molds such as core boxes against sand erosion, that may be readily practiced and applied in the core box room to avoid taking the molds out of production for any appreciable time.

Another object of the invention is to provide erosion barrier means for core boxes or other sand molds, that can readily be installed or applied or replaced quickly and With minimum interference with production.

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of certain preferred embodiments thereof taken in conjunction with the accompanying drawing, in which:

Figure 1 is a top plan view of the lower or base half portion of a sand core box embodying features of the invention;

Figure 2 is a transverse, vertical sectional view through the core box base portion of Figure 1, taken substantially along the line IIII, and showing the same in assembly with an upper or complementary companion portion and, more or less schematically, a sand blowing machine hopper and blow plate assembly associated therewith in process of blowing a core within the cavity provided by the core box assembly;

Figure 3 is a greatly enlarged fragmentary sectional States atent p r A 1C6 a en ed July so, 1957 2' detail viewtaken' substantially on the line III-III of Figure 1;

Figure 4 is a fragmentary sectional detail view similar to Figure 3 but showing a modification; and

Figure 5 is another fragmentary sectional detail view similar to Figures 3 and 4'but showing a further modification. V

In order to provide effective visualization of an embodiment of the invention, a core box as shown in Figures 1 and 2 has been selected including a bottom or base plate or box portion with which an upper complementary, matching box portion 11 is'assembled in use to provide a core cavity 12. This'cavity may be of any preferred shape or contours to producea sand core by blowing into the cavity core sand 13 from a hopper 14'of a core blowing machine through a blow plate 15. ,Appropriately located orifices or holes 17 in the blow plate 15 register with blow holes 18or tubes inthe upper core box member 11 communicatingwiththecavity 12in proper oifset relation to screened vent openings 19 in the bottom or base core box member '10 and moreparticularly in a base A member 10 aboutthe cavity 12 fits sea'lingly' into a matching groove 24 in the opposing faceof the" upper core box member 11 abouttlie'cavity 12; Such a seal is the subject. matter of another of my inventions" and does not form a part of the;prese'nt invention.

As the'core sand 13 isblown under strong air pressure through the blow plate ports or orifices 17 it travels with considerable acceleration through the blow holes 18 and enters the core cavity 12 as a stream or jet 25 of substantial force as is necessary to attain a thoroughly compacted sand core mass to fill the cavity 12. However, especially in the initial stages of blowing the cores the sand streams or jets- 25 impinge forceably against the base wall 20 of the lower core box member 10. This has an eroding effect upon the surface of the base. wall 20. After several core blowings, such erosion may be deep enough to affect d'etrimentally the desired contour of the core due to eroding out of a depressionor recess in the base wall 21) opposite the respective blow hole 18 in each instance. When the erosion has progressed beyond the tolerance stage insofar as the core contour is concerned, repair must bemade before the core box can be put back into production. 7

According to the present invention, however, I eliminate the need for repairing the core box wall 20 by providing a barrier against erosion on the core box cavity surface at each place' where the sand stream or jet from each of the blow holes 18 impinges thereagainst. Such a barrier is preferably in the form of an applied disk or wafer or patch film 27 of a material that'is effectively resistant to the erosive effect of the sand blown thereagainst. The barrier disks 27 should be large enough to receive substantially the full impact or force of the stream or jet 25 throughout the target area of impingement of the jet. That is, the disks 27 should be large enough and cover a large enough area to take the force of all sand driven against the wall surface 20 with erosive elfect.

In order to avoid interfering with the core contours, the barrier disks 27 should be as thin as practicable consistent with eflicient wearing qualities. The disks 27 should also be of a material that is easily handled and applied and may be of various sizes or provided in a form that is separable into desirable sizes to take care of various size areas. Moreover, it is desirable that the disks 27 be conformable to various contours within the core box cavity such, for example,'as the generally V-shaped contour shown in Figure 2.

In a desirable form, the wafers or disks 27- may be of an elastomeric material of substantially wafer thinness applicable to the core box surface to be protected by means of a suitable adhesive 28 (Fig. 3). One satisfactory form of such a material may comprise a tape-like film of essentially a copolymer of vinyl chloride provided as a pressure-sensitive adhesive sheet. Examples of such material are found in U. S. Patent No. 2,559,990. The desirability of such material-resides in that the wafer thin disk 27 has the adhesive 28 thereon in a'pressuresensitive form so as to be readily applicable without preparation other than generally cleaning the area towhich the self adhering disk or wafer 27 is to be applied by pressing the same against the surface 20. Furthermore, the resilience of the elastomeric material, aided by the cushion of adhesive between the barrier member 27 and the surface 20 has extremely high resistance to sand blast erosion by reason of its resilient cushioning yieldability to impingement of the sand particles thereagainst. Another advantage of this material is that should.

it become damaged in some way it can readily be ripped off and replaced by another barrier wafer disk 27.

While a natural or synthetic rubber or elastomer may be used in the barrier disks 27, other materials such as synthetic plastics or treated paper or cloth or felted material may be used. If preferred, the thin pads or wafers for protection against erosion may comprise thin metal sheet or foil such as aluminum foil, copper foil, magnesium foil, or the like in the form of a wafer 27a Figure 4 bonded to the surface 20 by means of a suitable adhesive 28a such as a cushioning type of material as may be provided by a rubber or similar cement.

Where the surface of the core must be maintained within fairly critical dimensions or contour, so that even a thin erosion barrier wafer would make too great a difference in such contour to be desirable, a recess 29 may be formed in the impingement or target area of the surface 20 (Fig. 5) so that a protective barrier wafer 27b may be secured therein flush with the surface 20.

It will be apparent that while the erosion patch barrier film or wafer material may be supplied in large sheets or strips or rolls and cut into pads or disks of the size and shape desired, the erosion barriers may also be supplied in suitably sized disks of whatever peripheral shape desired whether round as shown in Figure 1 or multilateral, to avoid the necessity of cutting them but enabling quick application to the areas desiredby simply selecting the size required for each such area. This is true whether the wafer disks or pads are of a non-metallic material or a metallic material such as a hard alloy foil.

If preferred, of course, a material may be provided which can be applied more or less permanently by heating the same by means of a heat lamp or by placing the same in an oven to set the same in the area to be protected or to set an adhesive by which a preformed film of the material is adapted to-be secured in place.

Erosion barrier pads according to the present invention are also suitable for application protectively on patterns in mold blowing operations and also where excessive wear is occurring on patterns in sand slinging molding operations.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. In a method of preventing erosion of internal surfaces of sand core boxes opposite the blow holes or blow tubes thereof, applying to the areas subject to erosion a thin film-like erosion resistant layer in the form of a flexible pad having thereon a pressure sensitive adhesive for bonding the pad to the respective area to be protected.

2. In a method of preventing erosion of internal surfaces of sand core boxes opposite the blow holes or blow tubes thereof, applying to the areas subject to erosion a film-like pad including as a major ingredient a copolymer of vinyl chloride, with a pressure sensitive adhesive on one side thereof engaged by manual pressure against the surface to be protected.

3. In a method of preventing erosion of internal surfaces of sand core boxes opposite the blow holes or blow tubes thereof, applying to the areas subject to erosion a thin foil-like erosion resistant metal layer adhesively applied to the surface area to be protected.

4. In a method of preventing erosion of internal surfaces of sand core boxes opposite the blow holes or blow tubes thereof, applying to the areas subject to erosion a preformed film-like pad of erosion resistant material by positioning the material in position over the area to be protected and then setting a retaining adhesive by heat treatment.

5. In a sand core box including separable core box members defining a core cavity therebetween, one of said members having openings therethrough communicating with said cavity for blowing sand into the cavity, the other of said members having on the areas thereof opposite the openings protective film-like erosion resistant material, said material being bonded directly onto the normal surface contours of said areas and being of such thinness that the surfaces of cores blown into the core box are substantially unaffected in contour where the surfaces of the cores bear against the protected areas.

6. In means for preventing erosion of internal surfaces of sand core boxes opposite the blow holes or blow tubes thereof, a flexible pad of a thin film-like erosion resistant layer of material, and a pressure sensitive adhesive on one face of said pad for bonding the pad to a normal surface area within a core box cavity opposite a blow hole or tube thereof and infinitely conformable to the normal contour of the area to be protected.

References Cited in the file of this patent UNITED STATES PATENTS 1,761,522 Elsey June 3, 1930 2,233,097 Hall Feb; 25, 1941 2,510,417 Rehklau June 6, 1950 2,553,627 Barlow May 22, 1951 2,659,119 Peterson Nov. 17, 1953 FOREIGN PATENTS 645,563 Great Britain Nov. 1, 1950 

1. IN A METHOD OF PREVENTING EROSION OF INTERNAL SURFACES OF SAND CORE BOXES OPPOSITE THE BLOW HOLES OR BLOW TUBES THEREOF, APPLYING TO THE AREAS SUBJECT TO EROSION A THIN FILM-LIKE EROSION RESISTANT LAYER IN THE FORM OF A FLEXIBLE PAD HAVING THEREON A PRESSURE SENSITIVE ADHESIVE FOR BONDING THE PAD TO THE RESPECTIVE AREA TO BE PROTECTED. 